Waste heat boiler



I 1,636,979 July 1927' H. s. BENNETT WASTE HEAT BOILER Filed May 14, 1920 Patented July 26, 1927.

'UNITED STATESPA N O HARRY SPENCER BENNETT, or RETRLERE I; rEims LvmIn, assI'onoR 'r o rm: 3A3- cocx & WILGQX'COKPANY, or BAYONNE, NEW- J RsEY, a CPRPORATION or m JERSEY.

Application fled Kay 14,

This invention relates to steam boilers of the water tube type and particularly boilers for utilizing the heat of waste gasesfrom open hearth steel furnaces or the like.

5 In the type of boilers to which the invention relates there is provided a series of inclined water tubes extending through a chamber across which baflies are arranged so that a series of passes are provided through which the hot gases travel in pass ing through the chamber, the'chamber generally being provided with a fiat roof which extends the entire length thereof. In such L construction the boiler water tubes at the front end of the chamber lie. only a short' distance beneath the roof of'the chamber and usually a series of superheater tubes are arranged beneath the roof of the'chamber and extend above the second pass and over lie the first baflle. Oomparatively little space therefore exists between the upper end of the first bafiie and the roof of the chamber and this space is more or less obstructed by the snperheater tubes. It has been found that this space is insuflicient to. permit free passage of the hot gases the result being that they are retarded in their'fiow by the restricted area above the baflie and by the superheater tubes arranged at this point. On account of such restriction and on account of the fact that in passing through such restricted area the gases are compelled to pa to a considerable extent longitudi nally of the superheater tubes it has been 7 found that solid matter is deposited upon the superheater tubes and other .parts adjacent thereto which frequently results in clogging the space between the tubes to such an extent as to seriously interfere, with the 1 operation of the boiler. This has been found articularly true where boilers of the type iieretofor'e described are employed --in utiliz: ing waste gases from steel furnaces.

The present invention aims to overcome this difiic'ulty and it has been (found that if the roof of the chamber and particularly that portion of the same lying above the first pass and part of the second pass be V elevated as hereinafter pointed out the dif- .ficulties mentioned will be overcome.

y such modification the space allowed for the passa e of gases above the first bafiie is materially increased so that the flow of gases wasrE mm nonline-v 1m. Serial No. 881,882. I will not be retarded and deposition of solid ,material on the superheater tubes or "other parts is obviated, this result probably being due in part to the factthat by means of such elevation of the roof of the chamber the'hot gases in travelling from'the first pass into the second pass of the boiler move to some extent transversely of the superheater tubes and do not travel longitudinally of sfich tubes to the same extent as in the prior constructions heretofore mentioned.

The present invention therefore results in producingva boiler which has marked advantages in operation and considerable increase in efliciengy over prior constructions in which the parts have not been modified in the manner stated. I

'The drawing accompanying this specification and forming a part thereof shows in longitudinal section a boiler of the type heretofore referred to having the present in- A vention embodied therein.

\ Referring to the drawing in detail 10 represents the front wall and 11 the rear wall of the boiler chamber it being understood that suitable side walls are also provided.

Arranged in the chamber is a bank'of water tubes 12 secured inheaders 13 and 14 arranged respectively at the. front and rear. of.

the chamber. 'The header 13 is' arranged at a higher elevation than the header l iwith the result that the water tubes 12 are inclined from the front toward the rear of thechamber. The headers 13 and 14 are'connected-by horizontal circulating tubes 15 and vertical tubes 16 to asteam and water drum 17 arranged at the top of the cham ber. Superheater tubes 18 are.mounted in the upperportion of the chamber and are secured in headers 19 and 20, one of which may be suitably connected to the steam space of the drum 17" and the other to a steam main (not shown) leading from the boiler. Arranged transversely of the cham- .berand spaced from the front wall thereof is a bridge wall 21 and above the samethere is arranged a baffle 22 which extends-from one side to the other of the chamber transversely of the water tubes and upwardly to approximately the height of the water tubes.' The wall 21 and bafile 22 may be generally designated as a front bafiie. At the rear of 105 the front baflle and spaced therefromthere baflle is also preferably not less than the area under the second or rear bafiie. I

While the roof of the chamber is prefer-.

is provided a wall extending from the roof of the chamber downwardly, beneath which there is arranged a baffle, 23, which extends from the wall 30 downwardly to approximately the bottom of the bank of water tubes. The wall 30 and bathe-.23 may be designated as a rear baffle. Asga result of the foregoing construction the [chamber ofthe boiler is divided into three passes through which the gases are forced to travel in pass-. ing through the boiler. '-When employed for utilizing waste gases from furnaces such gases are admitted to the chamber through a pi e 24, thei-n'let of which is arranged in the rst pass of the boiler. chamber. An exit opening 25 for the spent gases is provided in any suitable .place in the Walls of the chamber preferably in the third pass above the water tubes. If desired the boiler may be arranged for utilizing solid fuel by providi'ng a grate in front of'the bridge wall 21.

The roof of the chamber, to the arrangement of which the present invention particularly relates, preferably consists of a portion 26"whi6h is supported in the usual way, as illustrated on the circulating tubes, and a portion27the' latter of which is elevated a substantial :distance with reference to the former." The portion of the roof of the chamber which is elevated extends from the front of the boiler rearwardly to-substantially the center thereof so that such elevated portion overlies the major portion of the first and second passes of the boiler. The front bafiie 22 is positioned beneath the-elevated portion of the roof and approximately at the center thereof and the superheater tubes for most of their length lie beneath such elevated portion of the roof. The'elevation of'the part 27 of the roof is such that the cross sectional area of the space between the upper-end of the front bafiie'22 and the elevated portion of the roof is considerably.

greater than that of prior constructions of this character, this area being approximately the same or only slightly less than the cross sectional area of the various passes of thep boiler. vThe eflective area above the front Iably arranged at two difierentelevations as shown, since elevation ofthe rear portion of thereof is unnecessary from the standpoint. of the present invention, it is, of course,.evi-;. dent that the entire roof of the chamber; may, if desired,-be' arranged at an elevation corresponding to-that ,of the portion'27 of the-construction illustrated. a

heater tubes and adjacent parts and the cloggang of the spaces between such tubes, is avoided, the construction as a Whole there- .fore possessing substantial advantages over prior constructions of this character in that dlfliculties of operation are obviated and a marked increase in efliciency is secured. By providing an elevated portlon of the roof scribed, the capacity and e ciency of the boiler is correspondingly increased.

By forming the superheater of U'tubes located beneath the horizontal circulating tubes, and byextending the superheater tubes horizontally acrossgthe down pass but only dpartially across the up pass, as illustrate the gases from the up pass flow upwardly past the superheater into the chamber formed by the elevated roof portion, and

then, after flowing downwardly over the horizontal circulating tubes as described above, the gases, pass across the tubes of the superheater. I A downward flow of dustladen, gases across horizontally extending tubes results in a lesserdeposit of dust than' an upward flow or a longitudinal flow. The arrangement therefore avoids, or partly avoids, the deposition ofdust from the gases and correspondingly increases the efiiciency of the superheater.

. Moreover, where a considerable number of boilers are employed for utillzln .waste gases from steel furnaces, amarked increase "111 plant eificiency results, since with my improved construction, shutting down of the boilers for purpose of cleaning is largely avoided and a much larger number of boilers. can therefore be kept constantly in use, thus avoiding loss of waste gases which takes lacewhen boilers are thrown out of operation. .With the improved construction practically all of the waste. gases from the furnaces can therefore be utilized and in addition. it'ghas been found that the smelting periodftvhich formerly required a period of twenty six hours when the old form of boilers was used, has been reduced to twentyfour hours.

1 -Havingthus described my invention what 'I claim as new and desire'to seeure b'y Letters Patent is: v

1. In a steam boiler, an upper steam and water drum, horizontally inclined water tubes and connections between the same and said steam and water drum and comprising horizontal water and steam eirculators, a .baflle extending across the tubes, a roof 10-- cated above said circulatorsytheportion of theroof above said balile'being elevated sub-- s tantially-abbve the circulators and provid- ,said clrculating said steam-and water drum and comprising water drum,

- horizontal water and steam circulators, a baflle extending across the tubes, a roof located above said circulators, the portion of the roof above said bafile being elevated substantially above the circulators and pro viding a free unobstructed space between the circulators and the roof, and a superheater located beneath sai d circulators and extending over the second pass and only partially over the first pass, whereby the gases from the first pass sweep upwardly over the circulating tubes into said space and thence downwardly overisaid circulating tubes and over the tubes of the superheater to the second pass.

3. Ina steam boiler, an upper steam and horizontally inclined water tubes and connections between the same and said steam and water drum and comprising horizontal water and steam circulators, a baflle extending across the tubes, a roof located above said circulators, the portion of the roof above said bafile being elevated substantially above the circulators and providing a free unobstructed space between the circulators and the roof, and a superheater comprising U tubes located beneath said circulators and extending over the second pass and only partially over the first pass and with the bent ends proximately above said baflie, whereby the gases from the first pass sweep upwardly overthe circulating and thence downwardly over said circulating tubes and the superheater tubes to the second pass.

4. In a steam boiler. an

water drum, horizontally inclined water tubes'and connections between the same and said steam and water drum and comprising horizontal water and .steam circulators. a baflle extendingacross the tubes, a roof located aboversaid circulators, the portion of the roof above said bafile being elegated sub stantially above the circulators and providing a free unobstructed space between. the circulators and'the roof, and a superheater comprising U tubes extending parallel to said eircui'ators above the second pass and with the bent ends of the superheater tubes said steam and ing a free unobstructed least in part of the tubes located aptubes into said space upper steam and tubes, W the portion of the roof above said baffle belators and and means located a proximately above said baflle, whereby t 1e gases from the first pass sweep upwardly overthe circulating tubes into said space and thence downwardly over said circulating tubes and the superheater tubes to the second pass.

5. In a steam boiler, an upper steam and water drum, horizontally inclined water tubes and connections between the same and water drum and comprising horizontal water and" steam circulators a baflle extending: across the tubes. a. roof located above said circulators, the portion of the roof above said ballie being elevated substantially above the circulators and providcirculators and the roof, located beneath said circulators. the headers of the superheater bein located beneath-the non-elevated part of the roofand the tubes at being located beneath the elevated portion of the roof but not extending space between the and a. superheater across the space above the first pass whereb the gases from the first pass sweep upwardly over the circulating tubes into said space and thence downwardly over said circulating-tubes and the superheater tubes to the second pass.

6. In a steam boiler, an upper steam and water drum, horizontally inclined water tubes and connections between the same and said steam and water drum and comprising horizontal waiter and steam circulators. a bafi'ie extending across the tubes a roof located above said circulators, the portion of the roof above said baflie being elevated substantially above the circulators and providing a free unobstructed space between the circulators and the roof. and means for-delivering waste-heat gases to said boiler. whereby the gases from the first passsweep upwardly over the circulating said space and thence downwardly over said circulating tubes to the second pass, the gases 'beingcmade to flow across all of the circulating tubes of the boiler before entering the second pass.

7. In a waste-heat steam boiler, an upper tubes into steam and water drum, horizontally in-' clined water tubes and connections between the same and said steam and water drum and comprising horizontalwater and steam clrculators, a bafiie' extend ng across the a roof located above said circulators.

ing. elevatedsubstantially above the circus tween the circulators and the roo steam and water drum, horizontally inclined and a superheater located beneath said cirwate'r tubes and connections between the .culators and extending over the second vpass same and said steam and water drum and and only partially over the first pass, wherecomprising horizontal water andsteam cirby the gases from the first pass sweep up- 5 eulators, a baflle extending across the tubes, wardly over the eirculatin tubes into said a. roof located above said circulators,.the space and thence downwar 1 over said cirortion of the roof above said baffle being eulating tubes and the super eater tubes to elevated substantially above the eirculators the second pass. v

and providing a free unobstructed sfpaee be- In testimony whereof I afiix my signature.

, means for delivering waste-heat gases to the boiler, HARRY SPENCER BENNETT. 

